Gross billings--the total value of all the stuff and coupons Groupon sells--is now shrinking, at least before adjusting for foreign exchange rates

The company's now modest growth is coming from a new business, selling stuff, which has less attractive cash-flow characteristics and lower margins

Groupon's effort to become profitable has led to drastic cuts in marketing costs, and these are hurting the company's growth. This transition--from hyper-growth to steady growth with profitability--likely has a ways to go.

The company's management team and board continues to turn over, with early backers like Howard Schultz leaving

The future viability and attractiveness of the company's core business, coupon sales, is now in doubt. Until Groupon demonstrates that merchants and customers love its service and will keep buying even with no marketing, this will remain a question.

Put all that together, and investors are justifiably wondering whether Groupon will ever achieve a state of steady, profitable growth.

(For what it's worth, I still think it will. But there will likely be several more quarters of pain before we get there.)